1. Field of the Invention:
The invention relates to standing valves of the type employed in the bottom of a submersible pumping apparatus for an oil well which prevents reverse fluid flow from the production casing back into the well whenever the pumping operation is interrupted or the pumping apparatus is removed from the well for servicing.
2. Description of the Prior Art:
This invention constitutes an improvement over the standing valve construction disclosed and claimed in co-pending application Ser. No. 50,921, filed June 21, 1979, entitled "High Flow Check Valve Apparatus" assigned to the same assignee as this application. Such co-pending application discloses a standing valve for oil wells wherein a plurality of check valve units are provided between two laterally spaced, parallel inlet and outlet passages. While the construction disclosed in said aforementioned co-pending application is completely functional to minimize the pressure drop involved in a standing valve when the check valves are in their open or flowing position, the disclosed construction required relatively complicated components which would only be produced by castings and complex machining operations. To reduce the manufacturing cost of this type of standing valve apparatus, and to simplify the assembly and servicing of the valve, it is desirable that the great majority of components of the standing valve be capable of being produced by simple machining operations. For example, it is desirable that all of the major fluid flow passages in the standing valve be defined by drilled holes in the main housing element, rather than by cast apertures.
Additionally, it is desirable that the standing valve be capable of being mounted directly adjacent to a tubing controlled sub-surface safety valve, which is now being required for installation in many wells, particularly oil wells drilled in the ocean floor.